0000000000341415
AUTHOR
Jean-louis Calais
Calculations of the geometry and optical properties ofFMgcenters and dimer (F2-type) centers in corundum crystals
CALCULATIONS OF THE GEOMETRY AND OPTICAL-PROPERTIES OF F-MG CENTERS AND DIMER (F-2-TYPE) CENTERS IN CORUNDUM CRYSTALS
Calculations of the ground and excited states ofF-type centers in corundum crystals
The semiempirical intermediate neglect of differential overlap method was used for calculating optical properties of ${\mathit{F}}^{+}$ and F centers (oxygen vacancy trapped one and two electrons, respectively) embedded into large quantum clusters, ${\mathrm{Al}}_{26}$${\mathrm{O}}_{39}$. The geometry was optimized for both the ground and excited states of defects. Calculated absorption and luminescence energies obtained for ${\mathit{F}}^{+}$ and F centers are in good agreement with experimental data. Their energy levels lie in the gap between the upper valence band and conduction band, like for similar centers in MgO and alkali halides. It is shown that the oxygen vacancy in corundum crys…